This invention relates to magnetic recording and reproducing apparatus, and particularly to the transmission of write data and read data signals between the read/write signal processing circuit and read/write amplifier which are used when data is recorded on a recording medium.
The conventional magnetic recording and reproducing apparatus is generally comprised of, as shown in FIG. 16, a disk-like magnetic recording medium 1, a magnetic head 10, a write/read (R/W) amplifier 32, an R/W signal processor 33, a controller 4, a microprocessor 5, a servo controller 6 and an interface (I/F) circuit 7. The R/W signal processor 33 is formed of a write data generator 38 and a read data reproducer 9.
The record data transmitted from a host computer (hereinafter, the host) not shown is supplied to the R/W signal processor 33 through the I/F circuit 7 and controller 4. The write data generator 38 converts this record data into a recording code which is suitable for being recorded on the magnetic recording medium 1. This code is supplied to the R/W amplifier 32, and fed to the magnetic head 10 by which it is written on the magnetic recording medium 1. When the data is read from the medium 1 by the magnetic head 10, it is amplified by the R/W amplifier 32 and then decoded by the read data reproducer 9 of the R/W signal processor 33. The decoded signal is fed through the controller 4 and I/F circuit 7 to the host.
The servo controller 6 and microprocessor 5 control the magnetic head 10 to be positioned on the magnetic recording medium 1 and control the medium 1 to be rotated. In the data side servo system, part of the data read from the medium 1 is used as servo data. The read data reproducer 9 extracts this servo data signal, H from the input data and used to control the magnetic head 10 to be positioned.
Also, the R/W signal processor 33 has a register, though not shown, by which the characteristics of respective portions can be switched. This register can be set in a programmable manner by a control signal which is, though not shown, fed from the microprocessor 5.
FIG. 17 is a block diagram of one example of the R/W amplifier 32 and R/W signal processor 33 shown in FIG. 16.
Referring to FIG. 17, the R/W amplifier 32 is comprised of a read amp. and write driver 11, a 1/2 prescaler 12, a read/write selector 13, a read buffer amplifier 14, and a write current source 15. The read amp. and write driver 11 is connected to the magnetic head 10 and has amplifiers and drivers of which the numbers are equal to that of the magnetic head. The R/W signal processor 33 has the write data generator 38 and read data reproducer 9, and the write data generator 38 has a write precompensation circuit 38a and an encoder 38b. 
The record data E supplied from the host through the I/F circuit 7 and controller 4 shown in FIG. 16 is converted by the encoder 38b into a recording code such as 1-7RLLC or 8/9GCR which is, as shown in FIG. 18(a), suitable for being recorded on the magnetic recording medium. This recording code is further processed to be a data pulse signal C, or shifted in edge phase at each data pattern, by the write precompensation circuit 38a in order that the peak shift due to the magnetization interference or the like can be reduced. The data pulse signal C is fed to the R/W amplifier 32. The data pulse signal C is a serial RZ (return-to-zero) code as shown in FIG. 18(b).
This data pulse signal C is converted by the 1/2 prescaler 12 of the R/W amplifier 32 into a NRZI (non-return-to-zero-inverted) code K as shown in FIG. 18(c). The current pulse according to this code K is supplied from the write driver 11 to the magnetic head 10. As a result, data is recorded on the magnetic recording medium 1 shown in FIG. 16.
In general, since the R/W amplifier 32 is located close to the magnetic head 10, the R/W amplifier 32 and the R/W signal processor 33 are separate integrated circuits (ICs) and connected by a film-shaped cable.
The read/write selector 13 is a switching circuit for read and write operations. It stops the operation of the write driver at the time of reading and stops the operation of the read amplifier at time of writing. The write current source 15 is used to set the output current from the write driver.
The read buffer amplifier 14 amplifies the analog read data signal from the read amplifier 11 and transmits it to the read data reproducer 9. The read data reproducer 9 reproduces the read data from the read signal D fed from the read buffer amplifier 14, decodes the recording code into the original data and supplies it to the controller 4 shown in FIG. 16.
The write data C transmitted between the R/W signal processor 33 and the R/W amplifier 32 is in the form of TTL or ECL level voltage.
The read data signal D transmitted between the R/W signal processor 33 and the R/W amplifier 32 is also in the form of an analog voltage level.
The magnetic disk player has been so far improved year after year in its data transfer speed. In order to further speed up the data transfer operation, it is necessary to consider the system for transmitting write data signal and read data signal between the R/W signal processor IC 33 and the R/W amplifier IC 32.
The film cable used for connecting these ICs has a low transmission capability, or it easily dulls the waveform of the high-frequency pulse signal.
The reason is that the cable is necessary to be flexible for easy mounting in the recording and reproducing apparatus and to be inexpensive for low cost of the apparatus, with the result that the cable has a high characteristic impedance and large loss in its conductor and insulator.
FIG. 19 shows the waveforms of write data pulse signal in the conventional magnetic disk player. When the write data train (1, 1, 0, 0, 1) of the recording code as shown in FIG. 19(a) is transmitted at high speed, the ideal pulse waveform is shown in FIG. 19(b), but the actual waveform is blunt as shown by the solid line in FIG. 19(c). When the blunt read signal is shaped in its waveform by the R/W amplifier 32, the obtained pulse signal is shifted in the phase relation between the leading and trailing edges as shown in FIG. 19(d). This phase shift is caused according to the crowded or scattered pulses (the distance between xe2x80x9c1xe2x80x9d bits) of the original data pattern shown in FIG. 19(a). In addition, the amplitude is reduced so that the level margin is decreased, causing error in data.
The data transfer speed of the magnetic disk player or the like has recently increased up to 10 MB/sec or above, and thus the specification for the timing margin has become strict. In the present magnetic disk player, since the RZ coding system is used for the write data transmission between the R/W signal processor IC and the R/W amplifier IC, the write data frequency at a transfer speed of 10 MB/sec is 90 MHz for 8/9GCR and 60 MHz for 1-7RLLC.
In the present magnetic disk player having a film cable of about 100-mm in length and connectors, the write data transmission line between the R/W signal processor IC and the R/W amplifier IC has an inductance component of 100 nH and a capacitance component of 20 pF or above considering the conductors on the wiring board and the input/output terminals of ICs, and thus the transmission frequency is limited to about 100 MHz even for ECL level. Therefore, in the present system, data cannot be transferred at a high speed of 20 MB/sec or above.
Also, even if a high-performance cable with the above drawback obviated is used, a high-speed drive buffer is needed and thus the consumption power and cost are increased.
In addition, there has been U.S. Pat. No. 5,404,250 as a related art.
It is an object of the invention to provide a magnetic recording and reproducing apparatus with the above problems solved, or capable of reducing the consumption power and the cost and also of speeding up the operation and a semiconductor integrated circuit for use in the apparatus.
According to one aspect of this invention, to achieve the above object, there is provided a magnetic recording and reproducing apparatus of which the R/W signal processor has the write data generator arranged to be of an interleave system and transmits/receives data to/from the R/W amplifier via a plurality of signal lines. In addition, the R/W amplifier of the invention has a compound circuit provided for the write data of the interleave system from the R/W signal processor and is formed as an integrated circuit.
Moreover, a 1/2 prescaler is provided at the output of the write data generator, thereby making it possible to transmit and receive write data in NRZI code.
Also, a differential buffer and receiver are provided, thereby making it possible to transmit and receive write data in the form of differential signals.
According to another aspect of the invention, there is provided a magnetic recording and reproducing apparatus in which a current mode output circuit is provided at the write data output portion of the R/W signal processor, and a current mode input circuit is provided at the write data input portion of the R/W amplifier so that the write data between the R/W signal processor and the R/W amplifier can be transmitted in a current mode.
Also, a current switching circuit is provided at the current mode output circuit, thereby making it possible to switch the output current on or off.
Moreover, a register is provided, thereby making it possible to set the current switching circuit in a programmable manner under the control of the microprocessor.
According to another aspect of the invention, there is provided a magnetic recording and reproducing apparatus in which a current mode output circuit is provided at the read data output portion of the R/W amplifier, and a current mode input circuit is provided at the read data input portion of the R/W signal processor so that the read data between the R/W signal processor and the R/W amplifier can be transmitted in a current mode.
Since the write data signal is transmitted between the R/W amplifier and the R/W signal processor via a plurality of signal lines according to the interleave system, the frequency of the signal transmitted on a single signal line can be reduced.
In addition, since the write data signal between the R/W amplifier and the R/W signal processor is transmitted in NRZI code, the signal frequency can be reduced.
Therefore, even though the R/W amplifier is formed as an IC and connected to the R/W signal processor by an inexpensive transmission line, the phases of the transmitted write data signal at its leading edges and trailing edges are prevented from shifting due to the waveform distortion.
Since the write data signal between the R/W amplifier and the R/W signal processor is transmitted in a current mode, the signal amplitude can be reduced, and thus the consumption power in the output circuit of the R/W signal processor can be decreased.
Also, since the read data signal between the R/W amplifier and the R/W signal processor is transmitted in a current mode, the signal amplitude can be reduced and thus the consumption power in the output circuit of the R/W amplifier can be decreased.
In addition, since the signal amplitude can be decreased by transmitting each signal in a current mode, the amount of generated noise can be decreased and noise can be prevented from entering in the surrounding circuits.
Moreover, since the input impedance of each current mode input circuit can be adjusted by bias current, impedance matching can be achieved without the need to add a termination resistor to the film cable which has its own characteristic impedance, and thus the number of components used can be decreased.
Thus, according to this invention, the write data signal between the R/W amplifier and the R/W signal processor can be transmitted at a low frequency, and the magnetic recording and reproducing apparatus can be operated at a high transfer speed and low consumption power.
According to this invention, the write data signal and read data signal between the R/W amplifier and the R/W signal processor can be transmitted in a small-amplitude current mode, and both low consumption power and high transfer speed can be achieved.
Also, since data of small amplitude is transmitted, the amount of noise generated can be reduced.
Moreover, since the output current can be adjusted by the microprocessor, impedance matching to the film cable can be achieved without use of a termination resistor, and thus the number of discrete components used can be decreased, resulting in low cost. In addition, since it is possible to save the space around the R/W amplifier IC which space is not wide enough for components to be mounted on, the recording and reproducing apparatus can be produced at low cost and small-sized.
Furthermore, according to this invention, the write data signal and read data signal can be transmitted in a current mode, and thus both high transfer speed and low consumption power can be achieved.
The other objects, features and advantages of the invention will be fully understood by the following description with reference to the accompanying drawings.